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1. Rhamnose in plants - from biosynthesis to diverse functions

   https://doi.org/10.1016/j.plantsci.2020.110687  

   Jiang, Nan; Dillon, Francisco M.; Silva, Alexander; Gomez-Cano, Lina; Grotewold, Erich (January 2021, Plant Science)

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2. Cell-free expression and characterization of multivalent rhamnose-binding lectins using bio-layer interferometry

   https://doi.org/10.1093/glycob/cwad018  

   Warfel, Katherine F.; Laigre, Eugénie; Sobol, Sarah E.; Gillon, Emilie; Varrot, Annabelle; Renaudet, Olivier; Dejeu, Jerome; Jewett, Michael C.; Imberty, Anne (March 2023, Glycobiology)

   Abstract Lectins are important biological tools for binding glycans, but recombinant protein expression poses challenges for some lectin classes, limiting the pace of discovery and characterization. To discover and engineer lectins with new functions, workflows amenable to rapid expression and subsequent characterization are needed. Here, we present bacterial cell-free expression as a means for efficient, small-scale expression of multivalent, disulfide bond-rich, rhamnose-binding lectins. Furthermore, we demonstrate that the cell-free expressed lectins can be directly coupled with bio-layer interferometry analysis, either in solution or immobilized on the sensor, to measure interaction with carbohydrate ligands without purification. This workflow enables the determination of lectin substrate specificity and estimation of binding affinity. Overall, we believe that this method will enable high-throughput expression, screening, and characterization of new and engineered multivalent lectins for applications in synthetic glycobiology. 

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3. L-Rhamnose Globally Changes the Transcriptome of Planktonic and Biofilm Escherichia coli Cells and Modulates Biofilm Growth

   https://doi.org/10.3390/microorganisms12091911  

   Hantus, Charlotte E; Moppel, Isabella J; Frizzell, Jenna K; Francis, Anna E; Nagashima, Kyogo; Ryno, Lisa M (September 2024, Microorganisms)

   L-rhamnose, a naturally abundant sugar, plays diverse biological roles in bacteria, influencing biofilm formation and pathogenesis. This study investigates the global impact of L-rhamnose on the transcriptome and biofilm formation of PHL628 E. coli under various experimental conditions. We compared growth in planktonic and biofilm states in rich (LB) and minimal (M9) media at 28 °C and 37 °C, with varying concentrations of L-rhamnose or D-glucose as a control. Our results reveal that L-rhamnose significantly affects growth kinetics and biofilm formation, particularly reducing biofilm growth in rich media at 37 °C. Transcriptomic analysis through RNA-seq showed that L-rhamnose modulates gene expression differently depending on the temperature and media conditions, promoting a planktonic state by upregulating genes involved in rhamnose transport and metabolism and downregulating genes related to adhesion and biofilm formation. These findings highlight the nuanced role of L-rhamnose in bacterial adaptation and survival, providing insight into potential applications in controlling biofilm-associated infections and industrial biofilm management. 

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4. A cross-sectional study of associations between the 13C-sucrose breath test, the lactulose rhamnose assay, and growth in children at high risk of environmental enteropathy

   https://doi.org/10.1016/j.ajcnut.2024.10.001  

   Shivakumar, Nirupama; Huq, Sayeeda; Paredes-Olortegui, Maribel; Konyole, Silvenus Ochieng; Devi, Sarita; Yazbeck, Roger; Owino, Victor O; Brouwer, Andrew F; Kosek, Margaret N; Kelly, Paul; et al (October 2024, The American Journal of Clinical Nutrition)
5. Nucleotide-level characterization and improvement of l -arabinose- and l -rhamnose-inducible systems in E. coli using a high-throughput approach

   https://doi.org/10.1093/nar/gkaf224  

   Kim, Nancy M.; Peng, Danqia; Sandoval, Nicholas R. (April 2025, Nucleic Acids Research)

   Abstract The commonly used arabinose- and rhamnose-inducible Escherichia coli promoters, PBAD and PRha, exhibit tight regulation through activation via their respective transcription factors, AraC and RhaS, alongside the cyclic AMP receptor protein. The mechanisms of these promoters have been characterized on a parts level, but nucleotide-level analysis has yet to be elucidated. Therefore, we describe here a massively parallel reporter assay that maps regulatory sites at the nucleotide level. The relative importance of nucleotides in each binding site is revealed, including loci not included in previous annotations. For PBAD, we confirm known sites and reveal novel binding sites involved in modulating gene expression. In PRha, we refine the length and sequence specificity of rhaI half-sites, updating previous annotations and providing nucleotide level insights into RhaS-mediated regulation. Mutations that lead to increased promoter strength, wider dynamic range, and altered basal expression are identified for both promoters. Engineered versions of PBAD and PRha promoters based on this data show improvements in dynamic range alongside a seven- and three-fold increase in promoter strength, respectively, with a slight increase in basal expression for the PBAD promoters and no significant increase for PRha. This work expands the genetic parts “toolkit” and increases the understanding of these important commonly used promoters. 

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